Titan, the largest moon of Saturn and the second largest in the solar system, is now officially the best place in the solar system to build a sand castle.
Researchers studying the formation of Titan's towering sand dunes, some reaching more than 300 feet high, have discovered that they're likely electrically-charged and highly resistant to motion. Similar to the way you generate static electricity after rubbing a balloon on your hair, Titan's non-silicate granules gather charge as they're blown across its surface and become sticky.
The findings are published in the most recent edition of the journal Nature Geoscience.
"If you grabbed piles of grains and built a sand castle on Titan, it would perhaps stay together for weeks due to their electrostatic properties," geophysicist and co-study author Josef Dufek of Georgia Tech said in a statement. "Any spacecraft that lands in regions of granular material on Titan is going to have a tough time staying clean. Think of putting a cat in a box of packing peanuts."
You can see a video of some of Titan's massive dunes as captured by the Cassini spacecraft in the video below.
To prove their electrostatic sand theory, the researchers simulated Titan's nitrogen-rich environment using a modified pressure vessel. They then added grains of naphthalene and biphenyl, two hydrocarbon compounds believed to exist on the moon's surface, and rotated the vessel for 20 minutes to recreate average surface wind speeds of 15 mph.
“All of the particles charged well, and about 2 to 5 percent didn’t come out of the tumbler,” co-author Josh Méndez Harper said. “They clung to the inside and stuck together. When we did the same experiment with sand and volcanic ash using Earth-like conditions, all of it came out. Nothing stuck.”
The discovery also solves one of the most perplexing mysteries about Titan's dunes. Despite surface winds that blow from east to west, the dunes themselves appear to lean in the opposite direction. Electrically-charged sand would explain how this phenomenon is able to develop.
“Titan’s extreme physical environment requires scientists to think differently about what we’ve learned of Earth’s granular dynamics,” Dufek added. “Landforms are influenced by forces that aren’t intuitive to us because those forces aren’t so important on Earth. Titan is a strange, electrostatically sticky world.”